They willingly faced danger, and 343 firefighters perished when the Twin Towers fell.

To remember their service, and to raise money for firefighter charities, there have been stair climbs across the country in recent years. Firefighters have climbed the equivalent of 110 flights of stairs in honor the 343 fallen firefighters on 9/11.

Hays firefighter Justin Choitz has participated in three stair climbs -- Red Rocks Park and Amphitheatre near Denver last year, Lucas Oil Stadium in Indianapolis in March, and Qwest Towers in Denver on the anniversary of the attacks this month..

Choitz, 39, has been a full-time firefighter in Hays for eight years; his first day on the job full-time was Sept. 11, 2004. Participating in the stair climbs was something he felt compelled to do, to remember those fallen firefighters on that fateful day.

"There's a lot of grief and burden that goes along with this job," Choitz said. 'Those guys came to work every morning, just like I do."

The stair climb in Indianapolis and the one earlier this month in Denver was in full gear, which weighed 72 pounds. Choitz, who weighs 180 pounds, had on his protective gear, wore his boots, and had strapped on his back his breathing apparatus. He also carried a tool to break through doors and a flashlight. On his second climb of 55 floors at Qwest Towers, Choitz used his breathing apparatus.

Choitz traveled to Denver in July to practice climbing in a smaller building, and he also trained on the stairs at the firehouse in Hays.

"The hardest about (the climb) was all the gear on, building up heat," he said.

Choitz was joined at Qwest Towers with five firefighters from other departments. Each wore a badge with the name and picture of a fallen firefighter from 9/11 attached to their uniform.

"We all got there and understood on Sept. 11, the (six) guys we climbed for climbed the towers the same way," Choitz said. "They got off the truck, they knew they had a job to do."

At Red Rocks last year, Choitz also climbed the steps in memory of another fallen firefighter at 9/11.

"It's sobering," he said. "You google those guys, find out about them. My first guy, he left teenage kids, wife at home."

Yet, Choitz and 342 other firefighters climbed those stairs.

"You can imagine a few of those guys knew it was a lost cause when they saw it," Choitz said of 9/11.

Yet, they climbed those stairs.

"They went in as a team, knew they could do the impossible," Choitz said.

Something about Choitz's makeup compelled him to become a firefighter.

"People will drive by an accident, and say, 'Somebody should do something,' " he said. "They see somebody injured. ... I took the calling to be that somebody. (The firefighters on 9/11) took the calling, knew what they had to do."